Could it be that it is trying to put your discipline object into the query to the repository rather than making the query and then transforming it? Try putting the select after the ToList to force it to evaluate the query before you try to do the transform...
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ChrisJul 6 '12 at 12:55

What does .Query() do? Is it running a query (or sp?) on the database?
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MaartenJul 6 '12 at 13:13

What are you trying to achive with the Distinct when calling it on a reference type? I would expect a reference comparison when testing equality, so you wouldn't achieve a distinct as I think you want it.
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MaartenJul 6 '12 at 13:16